1. Field of the Invention
The invention relates in general to an error correction technique, and more particularly, to an application employing a dual error correction mechanism.
2. Description of the Related Art
With advancements in communication techniques, digital television broadcasting gradually matures. Apart from being transmitted via cables, digital television signals can also be transmitted in a form of wireless signals via a base station or a satellite. The Digital Video Broadcasting—Second Generation—Terrestrial (DVB-T2) and the Digital Video Broadcasting—Satellite—Second Generation (DVB-S2) are prevalent standards in digital television broadcasting.
To ensure image quality at a reception terminal is not excessively affected during the signal transmission process, a dual error correction mechanism is employed at a transmission terminal of both of the above digital television broadcasting systems—a Boss-Chaudhuri-Hocquenghem (BCH) error-correcting code and a low-density parity check (LDPC) error-correcting code. Correspondingly, a reception terminal of a digital television broadcasting system needs to first perform LDPC error correction and BCH error correction. The BCH error correction is fast and low power-consuming, and primarily serves for reexamination.
The LDPC error correction is a sequentially performed iteration procedure. An error correction process commonly adopted by most digital television broadcasting reception terminals is as the flowchart shown in FIG. 1. In step S11, LDPC error correction is performed on an input signal. In step S12, it is determined whether the number of times or the total amount of time of the LDPC error correction reaches an upper limit, which selectively involves an upper number limit and an upper time limit. Step S13 is performed when a determination result of step S12 is negative. For example, the upper number limit of LDPC error correction may be set to five times, and the upper time limit of the error correction may be the time point at which a next data packet arrives. Step S14 is performed when the determination result of step S12 is affirmative to directly perform BCH error correction on an output result of the LDPC error correction. In step S13, it is determined whether a current corrected result still contains errors. Step S11 is again performed when a determination result of step S13 is negative, until the determination result of step S12 is affirmative or the determination result of step S13 is negative.
As seen from FIG. 1, every time an input signal is at a high error level, the examination of step S13 is usually failed. As such, step S11 may be repeatedly performed for quite a number of times before the number of times or the amount of time of the LDPC correction performed reaches the upper limit, such that the total time for error correction is remarkably increased and an overall performance of a reception terminal of a digital television broadcasting system is thus degraded.